Vector magnetic field intensity measurement method and digital vector magnetoresistive magnetometer

Abstract

The present application provides a vector magnetic field strength measurement method and a digital vector magnetoresistive magnetometer, which can solve the problems of complex circuit design, difficulty in miniaturization, and high material cost of existing magnetoresistive magnetometers. The vector magnetic field strength measurement method is applied to a digital vector magnetoresistive magnetometer, including: obtaining a first analog signal, a second analog signal, and a third analog signal according to the magnetic field strength of the environment; performing signal processing on the first analog signal, the second analog signal, and the third analog signal respectively to obtain a first digital signal, a second digital signal, and a third digital signal; performing digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal, and the third digital signal respectively to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction, and the third direction.

Description

Technical Field

[0001] The present application relates to the technical field of vector magnetic field measurement, and in particular to a vector magnetic field intensity measurement method and a digital vector magnetoresistive magnetometer. Background Art

[0002] A vector magnetoresistive magnetometer is a sensor that works on the principle of magnetoresistive effect. It has the advantages of high voltage magnetic field conversion coefficient, low power consumption, and strong anti-interference ability. It has been widely used in navigation, non-destructive testing, automotive electronics, smart devices and other fields. For example, it is used in portable non-destructive testing equipment to detect material defects, corrosion or stress, or in spacecraft, satellites and space probes to detect the magnetic field characteristics of outer space.

[0003] Existing magnetoresistive magnetometers generally use analog circuits for modulation, demodulation and compensation. However, the use of analog circuits for modulation, demodulation and compensation has the following main disadvantages: the circuit design is complex, difficult to miniaturize, and the material cost is high; adjusting the working parameters of the magnetoresistive magnetometer requires replacing electronic components, which is complex to operate and technically difficult. Summary of the invention

[0004] In view of the above technical problems, the advantage of the present application is that it provides a vector magnetic field strength measurement method and a digital vector magnetoresistive magnetometer, which can solve the problems of complex circuit design, difficulty in miniaturization and high material cost of existing magnetoresistive magnetometers.

[0005] Another advantage of the present application is to provide a digital vector magnetoresistive magnetometer, wherein in order to achieve the above advantages, no expensive materials or complex structures are required in the present application. Therefore, the solution provided by the present application can successfully and effectively solve the above problems, and not only provides a simple digital vector magnetoresistive magnetometer, but also increases the practicality and reliability of the digital vector magnetoresistive magnetometer.

[0006] Based on this, in order to achieve at least one of the above advantages or other advantages and purposes of the present application, the present application provides a vector magnetic field strength measurement method, which is applied to a digital vector magnetoresistive magnetometer, and the method includes: According to the magnetic field strength of the environment in which the digital vector magnetoresistive magnetometer is located, a first analog signal, a second analog signal and a third analog signal are obtained, wherein the first analog signal represents a component of the magnetic field strength in a first direction, the second analog signal represents a component of the magnetic field strength in a second direction, and the third analog signal represents a component of the magnetic field strength in a third direction, and the first direction, the second direction and the third direction are perpendicular to each other; Performing signal processing on the first analog signal, the second analog signal and the third analog signal respectively to obtain a first digital signal, a second digital signal and a third digital signal; The first digital signal, the second digital signal and the third digital signal are respectively digitally orthogonally demodulated and digitally compensated to obtain the magnetic field intensity values ​​and phases of the magnetic field intensity in the first direction, the second direction and the third direction.

[0007] In this way, the vector magnetic field strength measurement method provided in the present application converts the first analog signal, the second analog signal and the third analog signal into a first digital signal, a second digital signal and a third digital signal, and then performs digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal and the third digital signal through digital operations, thereby obtaining the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction and the third direction, thereby solving the problems of complex circuit design, difficulty in miniaturization and high material cost in the prior art.

[0008] According to an embodiment of the present application, the first digital signal, the second digital signal, and the third digital signal are digitally orthogonally demodulated and digitally compensated respectively to obtain the magnetic field intensity values ​​and phases of the components of the magnetic field intensity in the first direction, the second direction, and the third direction, including: Generate a first phase reference signal and a second phase reference signal based on a demodulation frequency input by an external device; Performing digital quadrature demodulation based on the first digital signal, the second digital signal, the third digital signal, the first phase reference signal, and the second phase reference signal to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal, and the amplitude and phase of the third digital signal; Based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage-magnetic field conversion coefficient and temperature, and the real-time ambient temperature, the amplitude of the first digital signal, the amplitude of the second digital signal, and the amplitude of the third digital signal are respectively converted into the magnetic field strength value of the first digital signal, the magnetic field strength value of the second digital signal, and the magnetic field strength value of the third digital signal, and digital compensation is performed.

[0009] With such a configuration, the first digital signal, the second digital signal, and the third digital signal can be digitally orthogonally demodulated with the help of the generated first phase reference signal and the second phase reference signal, which can improve the signal's anti-interference ability and improve the signal's quality, while simplifying the hardware design and reducing the reliance on analog circuit devices. In addition, using digital orthogonal demodulation to demodulate the signal can be more conveniently integrated with other digital signal processing modules, reduce the overall hardware cost of the system, improve the overall reliability and stability of the system, and support the compatibility of multiple standards to meet the diverse needs of modern communication systems.

[0010] According to an embodiment of the present application, the digital quadrature demodulation is performed based on the first digital signal, the second digital signal, the third digital signal, the first phase reference signal, and the second phase reference signal to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal, and the amplitude and phase of the third digital signal, including: Mix and multiply the first digital signal, the second digital signal and the third digital signal with the first phase reference signal and the second phase reference signal, respectively, to obtain a first mixing signal and a second mixing signal corresponding to the first digital signal, a third mixing signal and a fourth mixing signal corresponding to the second digital signal, and a fifth mixing signal and a sixth mixing signal corresponding to the third digital signal, respectively; Digitally filter the first mixing signal and the second mixing signal, the third mixing signal and the fourth mixing signal, the fifth mixing signal and the sixth mixing signal to obtain a first in-phase component and a first quadrature component, a second in-phase component and a second quadrature component, and a third in-phase component and a third quadrature component respectively; The first in-phase component and the first quadrature component, the second in-phase component and the second quadrature component, and the third in-phase component and the third quadrature component are transformed into polar coordinates to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal, and the amplitude and phase of the third digital signal.

[0011] According to an embodiment of the present application, based on the relationship between the preset zero drift and the temperature, the relationship between the preset voltage-magnetic field conversion coefficient and the temperature, and the real-time ambient temperature, the amplitude of the first digital signal, the amplitude of the second digital signal, and the amplitude of the third digital signal are respectively converted into the magnetic field intensity value of the first digital signal, the magnetic field intensity value of the second digital signal, and the magnetic field intensity value of the third digital signal, and digital compensation is performed, specifically as follows: Based on the relationship between the preset voltage magnetic field conversion coefficient and the temperature, the amplitude of the first digital signal, the amplitude of the second digital signal and the amplitude of the third digital signal are converted into the magnetic field intensity value of the first digital signal, the magnetic field intensity value of the second digital signal and the magnetic field intensity value of the third digital signal respectively; Based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage magnetic field conversion coefficient and temperature, and the real-time ambient temperature, the magnetic field strength value of the first digital signal, the magnetic field strength value of the second digital signal, and the magnetic field strength value of the third digital signal are digitally compensated.

[0012] With such a setting, digital compensation can be performed based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage-magnetic field conversion coefficient and temperature, and the real-time ambient temperature, that is, the errors of each measured magnetic field strength value are corrected by digital software calculation, thereby avoiding the occurrence of a situation where the accuracy of each measured magnetic field strength value is affected by the error, and the digital compensation method adopted in this scheme can modify or adjust the algorithm or code accordingly according to different actual needs, while the scheme of compensation through analog circuits in the prior art needs to modify the real analog circuit according to different actual needs. Therefore, the scheme provided by the present application is more flexible and more environmentally adaptable than the scheme of the prior art because it does not require modification of the hardware.

[0013] According to an embodiment of the present application, generating a first phase reference signal and a second phase reference signal based on a demodulation frequency input by an external device includes: Generate a first phase reference signal based on a demodulation frequency input by an external device; The first phase reference signal is phase-shifted to obtain a second phase reference signal.

[0014] According to one embodiment of the present application, the vector magnetic field strength measurement method further includes: heating the digital vector magnetoresistive magnetometer to a first temperature, and recording a first relationship between a measurement value of the digital vector magnetoresistive magnetometer and temperature during cooling to a second temperature under the first magnetic field strength; Cooling the digital vector magnetoresistive magnetometer to a third temperature, and recording a second relationship between a measurement value of the digital vector magnetoresistive magnetometer and temperature during a process of naturally heating up to a second temperature under the first magnetic field strength; Based on the first relationship and the second relationship, obtaining a relationship between a preset zero drift and a temperature; heating the digital vector magnetoresistive magnetometer to a first temperature, and recording a third relationship between a voltage-to-magnetic-field conversion coefficient and temperature of the digital vector magnetoresistive magnetometer during cooling to a second temperature under a second magnetic field strength; Cooling the digital vector magnetoresistive magnetometer to a third temperature, and recording a fourth relationship between a voltage-to-magnetic-field conversion coefficient and temperature of the digital vector magnetoresistive magnetometer during a process of naturally heating to the second temperature under a second magnetic field strength; Based on the third relationship and the fourth relationship, a relationship between a preset voltage-magnetic field conversion coefficient and temperature is obtained.

[0015] According to an embodiment of the present application, performing signal processing on the first analog signal, the second analog signal, and the third analog signal to obtain a first digital signal, a second digital signal, and a third digital signal respectively includes the following steps: Generate a square wave modulation signal of a specific frequency, and based on the square wave modulation signal, perform square wave modulation on the first analog signal, the second analog signal, and the third analog signal respectively; performing differential amplification and filtering on the first analog signal, the second analog signal and the third analog signal respectively; Based on the trigger signal, the first analog signal, the second analog signal and the third analog signal are respectively converted into digital form to obtain a first digital signal, a second digital signal and a third digital signal.

[0016] In this way, differential amplification and filtering of analog signals before converting them into digital signals can significantly improve signal quality and the accuracy of subsequent digital processing. Differential amplification enhances useful signals by eliminating common-mode noise (such as power supply noise or environmental interference), which is particularly suitable for weak signals or high-noise environments, thereby improving the signal-to-noise ratio of the signal. Filtering can remove high-frequency noise or low-frequency interference in the signal, retain the signal components of the target frequency band, avoid aliasing effects, and ensure that the digitized signal is purer and more accurate. In addition, this type of differential amplification and filtering can reduce the impact of temperature drift and nonlinear distortion on digital signals, so as to improve the overall stability of the system and lay a good foundation for subsequent digital orthogonal demodulation and digital compensation of digital signals.

[0017] According to another aspect of the present application, the present application further provides a digital vector magnetoresistive magnetometer, the digital vector magnetoresistive magnetometer is used to measure the magnetic field intensity of a three-dimensional vector magnetic field, and the digital vector magnetoresistive magnetometer includes: Three-axis magnetoresistive module, signal processing module and digital processing module; The three-axis magnetic resistance module is used to obtain a first analog signal, a second analog signal and a third analog signal according to the magnetic field strength of the environment, wherein the first analog signal represents the component of the magnetic field strength in a first direction, the second analog signal represents the component of the magnetic field strength in a second direction, and the third analog signal represents the component of the magnetic field strength in a third direction, and the first direction, the second direction and the third direction are perpendicular to each other; The signal processing module is used to perform signal processing on the first analog signal, the second analog signal and the third analog signal respectively to obtain a first digital signal, a second digital signal and a third digital signal; The digital processing module is used to perform digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal and the third digital signal respectively to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction and the third direction.

[0018] According to one embodiment of the present application, the signal processing module includes a square wave modulation unit, a signal conditioning unit and a synchronous acquisition unit; The square wave modulation unit is used to perform square wave modulation on the first analog signal, the second analog signal and the third analog signal respectively based on the square wave modulation signal; The signal conditioning unit is used to perform differential amplification and filtering on the first analog signal, the second analog signal and the third analog signal respectively; The synchronous acquisition unit is used to perform analog-to-digital conversion on the first analog signal, the second analog signal and the third analog signal respectively based on the trigger signal to obtain a first digital signal, a second digital signal and a third digital signal; The digital processing module is also used to generate a square wave modulation signal and a trigger signal of a specific frequency.

[0019] According to an embodiment of the present application, the signal conditioning unit includes a differential amplifier circuit and an active low-pass filter circuit, and the operational amplifier in the differential amplifier circuit is a zero-drift operational amplifier, and the resistor in the signal conditioning unit is a low-temperature drift resistor.

[0020] In this way, the use of zero-drift operational amplifiers and low-temperature drift resistors in differential amplifier circuits can significantly improve the overall accuracy and stability of the system. The zero-drift operational amplifier can effectively eliminate input offset voltage and temperature drift through its internal calibration technology, ensuring high accuracy over a wide temperature range; while the low-temperature drift resistor can reduce the impact of temperature changes on circuit gain and bias, thereby reducing system errors to ensure the accuracy of signals in complex environments.

[0021] Beneficial effect: Compared with the prior art that uses an analog circuit to modulate, demodulate and compensate the first analog signal, the second analog signal and the third analog signal to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction and the third direction, the vector magnetic field strength measurement method provided in the present application converts the first analog signal, the second analog signal and the third analog signal into a first digital signal, a second digital signal and a third digital signal, and then performs digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal and the third digital signal through digital calculation, so as to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction and the third direction, thereby solving the problems of complex circuit design, difficulty in miniaturization and high material cost in the prior art, which not only improves the overall integration of the digital vector magnetoresistive magnetometer, but also reduces the cost of the digital vector magnetoresistive magnetometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A flow chart of a method for measuring vector magnetic field strength provided for one embodiment of the present application; Figure 2 A structural block diagram of a digital vector magnetoresistive magnetometer provided in another embodiment of the present application; Figure 3 A structural block diagram of a digital vector magnetoresistive magnetometer provided for other embodiments of the present application; Figure 4 A circuit connection diagram of a differential amplifier circuit and an active filter circuit provided in another embodiment of the present application; Figure 5 A structural block diagram of a digital processing module provided in another embodiment of the present application; Figure 6 A digital processing effect diagram provided for another embodiment of the present application; Figure 7 A digital compensation effect diagram provided for another embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0025] Considering that the existing magnetoresistive magnetometers generally use analog circuits for modulation, demodulation and compensation, the use of analog circuits for modulation, demodulation and compensation has the following main disadvantages: the circuit design is complex, difficult to miniaturize, and the material cost is high; adjusting the working parameters of the magnetoresistive magnetometer requires the replacement of electronic components, which is complex to operate and has high technical difficulty. In order to solve this problem, the present application provides a vector magnetic field intensity measurement method and a digital vector magnetoresistive magnetometer, which can solve the problems of the existing magnetoresistive magnetometer circuit design being complex, difficult to miniaturize, and having high material cost.

[0026] For details, please refer to the attached Figure 1An embodiment of the present application provides a method for measuring vector magnetic field strength, which is applied to a digital vector magnetoresistive magnetometer. The method includes: S1. According to the magnetic field strength of the environment in which the digital vector magnetoresistive magnetometer is located, a first analog signal, a second analog signal and a third analog signal are obtained, wherein the first analog signal represents the component of the magnetic field strength in a first direction, the second analog signal represents the component of the magnetic field strength in a second direction, and the third analog signal represents the component of the magnetic field strength in a third direction, and the first direction, the second direction and the third direction are perpendicular to each other.

[0027] Exemplarily, the first analog signal is an analog signal representing the magnetic field intensity component of the magnetic field intensity in a first direction, the second analog signal is an analog signal representing the magnetic field intensity component of the magnetic field intensity in a second direction, and the third analog signal is an analog signal representing the magnetic field intensity component of the magnetic field intensity in a third direction. The first direction, the second direction, and the third direction are the positive direction or the negative direction of the X-axis, the Y-axis, or the Z-axis.

[0028] S2. Perform signal processing on the first analog signal, the second analog signal and the third analog signal respectively to obtain a first digital signal, a second digital signal and a third digital signal.

[0029] Exemplarily, the signal processing process includes steps such as square wave modulation, differential amplification, filtering, and analog-to-digital conversion.

[0030] S3. Perform digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal and the third digital signal respectively to obtain the magnetic field intensity values ​​and phases of the magnetic field intensity in the first direction, the second direction and the third direction.

[0031] That is, digital orthogonal demodulation and digital compensation are performed on the first digital signal to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, digital orthogonal demodulation and digital compensation are performed on the second digital signal to obtain the magnetic field strength value and phase of the magnetic field strength in the second direction, and digital orthogonal demodulation and digital compensation are performed on the third digital signal to obtain the magnetic field strength value and phase of the magnetic field strength in the third direction.

[0032] Exemplarily, digital orthogonal demodulation is the process of performing orthogonal demodulation on a digital signal through software code to obtain the amplitude and phase of the digital signal, and digital compensation is the process of performing temperature compensation on the digital signal based on the real-time ambient temperature through software code to avoid the influence of the ambient temperature on the measured magnetic field strength.

[0033] It should be noted that, compared with the prior art in which the first analog signal, the second analog signal and the third analog signal are modulated, demodulated and compensated by an analog circuit to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction and the third direction, the vector magnetic field strength measurement method provided in the present application converts the first analog signal, the second analog signal and the third analog signal into a first digital signal, a second digital signal and a third digital signal, and then performs digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal and the third digital signal through digital calculations to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction and the third direction, thereby solving the problems of complex circuit design, difficulty in miniaturization and high material cost in the prior art, which not only improves the overall integration of the digital vector magnetoresistive magnetometer, but also reduces the cost of the digital vector magnetoresistive magnetometer.

[0034] In other embodiments of the present application, the first digital signal, the second digital signal, and the third digital signal are digitally orthogonally demodulated and digitally compensated respectively to obtain the magnetic field intensity values ​​and phases of the components of the magnetic field intensity in the first direction, the second direction, and the third direction, including: S31. Generate a first phase reference signal and a second phase reference signal based on a demodulation frequency input by an external device.

[0035] It should be noted that the demodulation frequency is the frequency of the first phase reference signal and the second phase reference signal.

[0036] S32. Perform digital orthogonal demodulation based on the first digital signal, the second digital signal, the third digital signal, the first phase reference signal and the second phase reference signal to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal and the amplitude and phase of the third digital signal.

[0037] That is, digital orthogonal demodulation and digital compensation are performed on the first digital signal to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, digital orthogonal demodulation and digital compensation are performed on the second digital signal to obtain the magnetic field strength value and phase of the magnetic field strength in the second direction, and digital orthogonal demodulation and digital compensation are performed on the third digital signal to obtain the magnetic field strength value and phase of the magnetic field strength in the third direction.

[0038] S33. Based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage-magnetic field conversion coefficient and temperature, and the real-time ambient temperature, the amplitude of the first digital signal, the amplitude of the second digital signal, and the amplitude of the third digital signal are respectively converted into the magnetic field strength value of the first digital signal, the magnetic field strength value of the second digital signal, and the magnetic field strength value of the third digital signal, and digital compensation is performed.

[0039] That is, based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage-magnetic field conversion coefficient and temperature, and the real-time ambient temperature, the amplitude of the first digital signal is converted into the magnetic field strength value of the first digital signal, and digital compensation is performed, the amplitude of the second digital signal is converted into the magnetic field strength value of the second digital signal, and digital compensation is performed, and the amplitude of the third digital signal is converted into the magnetic field strength value of the third digital signal, and digital compensation is performed.

[0040] It should be noted that the relationship between the zero point drift and temperature is the relationship between the measurement zero point of the digital vector magnetoresistive magnetometer and the temperature change, and the relationship between the voltage-magnetic field conversion coefficient and temperature is the relationship between the conversion coefficient of the amplitude of the digital signal into the magnetic field intensity and the temperature change.

[0041] It should be noted that the first digital signal, the second digital signal and the third digital signal can be digitally orthogonally demodulated with the help of the generated first phase reference signal and the second phase reference signal, which can improve the anti-interference ability of the signal, improve the quality of the signal, simplify the hardware design, and reduce the dependence on analog circuit devices. In addition, using digital orthogonal demodulation to demodulate the signal can be more conveniently integrated with other digital signal processing modules, reduce the overall hardware cost of the system, improve the overall reliability and stability of the system, and support the compatibility of multiple standards to meet the diverse needs of modern communication systems.

[0042] In other embodiments of the present application, the digital quadrature demodulation is performed based on the first digital signal, the second digital signal, the third digital signal, the first phase reference signal, and the second phase reference signal to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal, and the amplitude and phase of the third digital signal, including: S321. Mix and multiply the first digital signal, the second digital signal and the third digital signal with the first phase reference signal and the second phase reference signal, respectively, to obtain a first mixing signal and a second mixing signal corresponding to the first digital signal, a third mixing signal and a fourth mixing signal corresponding to the second digital signal, and a fifth mixing signal and a sixth mixing signal corresponding to the third digital signal.

[0043] That is, the first digital signal is mixed and multiplied with the first phase reference signal and the second phase reference signal to obtain a first mixing signal and a second mixing signal corresponding to the first digital signal, the second digital signal is mixed and multiplied with the first phase reference signal and the second phase reference signal to obtain a third mixing signal and a fourth mixing signal corresponding to the second digital signal, and the third digital signal is mixed and multiplied with the first phase reference signal and the second phase reference signal to obtain a fifth mixing signal and a sixth mixing signal corresponding to the third digital signal.

[0044] It should be noted that the mixing and multiplication refers to an operation of directly multiplying two signals in the time domain.

[0045] S322, digitally filter the first mixing signal and the second mixing signal, the third mixing signal and the fourth mixing signal, the fifth mixing signal and the sixth mixing signal, respectively, to obtain a first in-phase component and a first quadrature component, a second in-phase component and a second quadrature component, and a third in-phase component and a third quadrature component, respectively.

[0046] That is, the first mixing signal and the second mixing signal are digitally filtered to obtain a first in-phase component and a first quadrature component, the third mixing signal and the fourth mixing signal are digitally filtered to obtain a second in-phase component and a second quadrature component, and the fifth mixing signal and the sixth mixing signal are digitally filtered to obtain a third in-phase component and a third quadrature component.

[0047] It is worth noting that the digital filtering includes digital low-pass filtering and integral comb filtering.

[0048] S323. Perform polar coordinate conversion on the first in-phase component and the first quadrature component, the second in-phase component and the second quadrature component, and the third in-phase component and the third quadrature component to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal, and the amplitude and phase of the third digital signal.

[0049] That is, the first in-phase component and the first orthogonal component are polar transformed to obtain the amplitude and phase of the first digital signal, the second in-phase component and the second orthogonal component are polar transformed to obtain the amplitude and phase of the second digital signal, and the third in-phase component and the third orthogonal component are polar transformed to obtain the amplitude and phase of the third digital signal.

[0050] It should be noted that polar coordinate conversion refers to the process of converting signals or data in a rectangular coordinate system (Cartesian coordinate system) into a polar coordinate system, that is, converting from (x, y) or (I, Q) form to amplitude (modulus) and phase (angle) form (r, θ).

[0051] In other embodiments of the present application, based on the relationship between the preset zero drift and the temperature, the relationship between the preset voltage-magnetic field conversion coefficient and the temperature, and the real-time ambient temperature, the amplitude of the first digital signal, the amplitude of the second digital signal, and the amplitude of the third digital signal are respectively converted into the magnetic field intensity value of the first digital signal, the magnetic field intensity value of the second digital signal, and the magnetic field intensity value of the third digital signal, and digital compensation is performed, including: S331. Based on the relationship between the preset voltage-magnetic field conversion coefficient and the temperature, the amplitude of the first digital signal, the amplitude of the second digital signal and the amplitude of the third digital signal are respectively converted into the magnetic field strength value of the first digital signal, the magnetic field strength value of the second digital signal and the magnetic field strength value of the third digital signal, that is, the amplitude of each digital signal is multiplied by the above-mentioned voltage-magnetic field conversion coefficient to obtain the magnetic field strength value of each digital signal.

[0052] That is, based on the relationship between the preset voltage magnetic field conversion coefficient and the temperature, the amplitude of the first digital signal is converted into the magnetic field strength value of the first digital signal, the amplitude of the second digital signal is converted into the magnetic field strength value of the second digital signal, and the amplitude of the third digital signal is converted into the magnetic field strength value of the third digital signal.

[0053] S332. Based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage magnetic field conversion coefficient and temperature, and the real-time ambient temperature, digitally compensate the magnetic field strength value of the first digital signal, the magnetic field strength value of the second digital signal, and the magnetic field strength value of the third digital signal.

[0054] It should be noted that digital compensation can be performed based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage-magnetic field conversion coefficient and temperature, and the real-time ambient temperature, that is, the errors of the measured magnetic field strength values ​​are corrected by digital software calculations, thereby avoiding the occurrence of a situation where the accuracy of the measured magnetic field strength values ​​is affected by errors, and the digital compensation method adopted in this scheme can modify or adjust the algorithm or code accordingly according to different actual needs. The scheme of compensation through analog circuits in the prior art needs to modify the real analog circuit according to different actual needs. Therefore, the scheme provided in this application is more flexible and more environmentally adaptable than the scheme of the prior art because it does not require modification of the hardware.

[0055] In other embodiments of the present application, generating the first phase reference signal and the second phase reference signal based on the demodulation frequency input by the external device includes: S311. Generate a first phase reference signal based on a demodulation frequency input by an external device.

[0056] It should be noted that the external device is a terminal or a host computer module described below.

[0057] S312: Perform a phase shift on the first phase reference signal to obtain a second phase reference signal.

[0058] In another embodiment of the present application, the generation of the first phase reference signal and the second phase reference signal based on the demodulation frequency input by the external device is specifically: Generate a first phase reference signal based on a demodulation frequency input by an external device; The first phase reference signal is phase-shifted by 90° to obtain a second phase reference signal.

[0059] In other embodiments of the present application, the vector magnetic field strength measurement method further includes: S4. Heating the digital vector magnetoresistive magnetometer to a first temperature, and recording a first relationship between a measurement value of the digital vector magnetoresistive magnetometer and temperature during cooling to a second temperature under the first magnetic field strength.

[0060] S5. Cool the digital vector magnetoresistive magnetometer to a third temperature, and record a second relationship between the measurement value of the digital vector magnetoresistive magnetometer and the temperature during a process of naturally heating up to the second temperature under the first magnetic field strength.

[0061] S6. Based on the first relationship and the second relationship, obtain a preset relationship between zero point drift and temperature.

[0062] S7. Heating the digital vector magnetoresistive magnetometer to a first temperature, and recording a third relationship between the voltage-to-magnetic-field conversion coefficient and the temperature of the digital vector magnetoresistive magnetometer during cooling to the second temperature under a second magnetic field strength.

[0063] S8. Cool the digital vector magnetoresistive magnetometer to a third temperature, and record a fourth relationship between the voltage-magnetic field conversion coefficient and the temperature of the digital vector magnetoresistive magnetometer during a process of naturally heating up to the second temperature under the second magnetic field strength.

[0064] S9. Based on the third relationship and the fourth relationship, obtain a relationship between a preset voltage-magnetic field conversion coefficient and temperature.

[0065] It is worth noting that, in another embodiment of the present application, the vector magnetic field strength measurement method further includes: Step 1: Place the digital vector magnetoresistive magnetometer in a high and low temperature device, set the temperature to +50°C, and after the temperature of the magnetometer is uniform, place it in a Permalloy shielding tube and cool it naturally to room temperature, and simultaneously record the changes in temperature and magnetic field output (in the form of analog signals and digital signals) over time.

[0066] It should be noted that the Permalloy shielding tube is a device used for electromagnetic shielding, usually made of high magnetic permeability Permalloy. Permalloy is a nickel-iron alloy (usually 70%-80% nickel and 20%-30% iron), with extremely high magnetic permeability and low coercivity, and can effectively shield low-frequency magnetic fields and electromagnetic interference (EMI).

[0067] Step 2: Place the digital vector magnetoresistive magnetometer in a high and low temperature device, set the temperature to -40°C, and after the temperature of the magnetometer is uniform, place it in a Permalloy shielding tube, naturally heat it to room temperature, and simultaneously record the changes in temperature and magnetic field output (in the form of analog signals and digital signals) over time.

[0068] It should be noted that the high and low temperature device is a device used to simulate changes in ambient temperature and can quickly raise and lower the ambient temperature within a specific temperature range.

[0069] Step 3: Obtain the curve of the measurement value (zero point) of the digital vector magnetoresistive magnetometer at zero magnetic field versus temperature through steps 1 and 2, and perform least squares fitting to obtain fitting parameters of the relationship between zero point drift and temperature.

[0070] It should be noted that the least squares method is a mathematical optimization technique used to find the best function match for data by minimizing the sum of squares of errors. Its basic idea is to fit a curve or function so that the sum of squares of errors between the curve and the actual observed data is minimized, so it is also used in curve fitting. The fitting parameter of the relationship between the zero point drift and temperature is the relationship between the measurement zero point of the vector magnetoresistive magnetometer and the temperature change.

[0071] Step 4: Use the coil to generate a vector magnetic field of a specific intensity in the Permalloy shielding tube, then perform steps 1 and 2 to obtain a curve of the voltage-magnetic field conversion coefficient of the digital vector magnetoresistive magnetometer changing with temperature, and perform least squares fitting to obtain fitting parameters of the relationship between the voltage-magnetic field conversion coefficient and temperature.

[0072] It should be noted that the fitting parameter of the relationship between the voltage-magnetic field conversion coefficient and temperature is the relationship between the conversion coefficient of the amplitude of the digital signal into the magnetic field intensity and the temperature change.

[0073] Step 5: Digitally compensate the output value of the digital vector magnetoresistive magnetometer according to the fitting parameters of the relationship between zero point drift and temperature, the fitting parameters of the relationship between voltage magnetic field conversion coefficient and temperature, and the real-time ambient temperature, that is, according to the obtained relationship between the measurement zero point of the digital vector magnetoresistive magnetometer and the temperature change, the relationship between the conversion coefficient of the amplitude of the digital signal to the magnetic field intensity and the temperature change, and the real-time ambient temperature, remove the error in the output value of the digital vector magnetoresistive magnetometer.

[0074] In other embodiments of the present application, the signal processing of the first analog signal, the second analog signal, and the third analog signal to obtain the first digital signal, the second digital signal, and the third digital signal respectively includes the following steps: A square wave modulation signal of a specific frequency is generated, and based on the square wave modulation signal, square wave modulation is performed on the first analog signal, the second analog signal and the third analog signal respectively.

[0075] It should be noted that the square wave modulation refers to the process of modulating each analog signal using the square wave of the specific frequency as a carrier.

[0076] performing differential amplification and filtering on the first analog signal, the second analog signal and the third analog signal respectively; It should be noted that differential amplification refers to improving signal fidelity and anti-interference capability by amplifying differential-mode signals and suppressing common-mode signals.

[0077] Based on the trigger signal, the first analog signal, the second analog signal and the third analog signal are respectively converted into digital form to obtain a first digital signal, a second digital signal and a third digital signal.

[0078] It should be noted that differential amplification and filtering of analog signals before converting them into digital signals can significantly improve signal quality and the accuracy of subsequent digital processing. Differential amplification enhances useful signals by eliminating common-mode noise (such as power supply noise or environmental interference), which is particularly suitable for weak signals or high-noise environments, thereby improving the signal-to-noise ratio of the signal. Filtering can remove high-frequency noise or low-frequency interference in the signal, retain the signal components of the target frequency band, avoid aliasing effects, and ensure that the digitized signal is purer and more accurate. In addition, this type of differential amplification and filtering can reduce the impact of temperature drift and nonlinear distortion on digital signals, so as to improve the overall stability of the system and lay a good foundation for subsequent digital orthogonal demodulation and digital compensation of digital signals.

[0079] In other embodiments of the present application, Figure 2As shown, a digital vector magnetoresistive magnetometer is provided, and the digital vector magnetoresistive magnetometer is used to measure the magnetic field strength of a three-dimensional vector magnetic field. The digital vector magnetoresistive magnetometer includes: Three-axis magnetoresistive module, signal processing module and digital processing module; The three-axis magnetoresistance module is used to obtain a first analog signal, a second analog signal and a third analog signal according to the magnetic field strength of the environment. The first analog signal represents the component of the magnetic field strength in a first direction, the second analog signal represents the component of the magnetic field strength in a second direction, and the third analog signal represents the component of the magnetic field strength in a third direction. The first direction, the second direction and the third direction are perpendicular to each other.

[0080] It should be noted that, in one embodiment of the present application, the three-axis magnetoresistive module has a multi-axis measurement function (magnetic field components in the X, Y, and Z axis directions), and can provide three-dimensional magnetic field measurement capabilities. The three output voltages of the three-axis magnetoresistive module are all differential output modes, that is, two signals with equal amplitudes and opposite phases are output, which are respectively called positive output (+) and negative output (-).

[0081] The signal processing module is used to perform signal processing on the first analog signal, the second analog signal and the third analog signal respectively to obtain a first digital signal, a second digital signal and a third digital signal.

[0082] In other embodiments of the present application, Figure 3 As shown, the signal processing module includes a square wave modulation unit, a signal conditioning unit and a synchronous acquisition unit; The square wave modulation unit is used to perform square wave modulation on the first analog signal, the second analog signal and the third analog signal respectively based on the square wave modulation signal; The signal conditioning unit is used to perform differential amplification and filtering on the first analog signal, the second analog signal and the third analog signal respectively; The synchronous acquisition unit is used to perform analog-to-digital conversion on the first analog signal, the second analog signal and the third analog signal respectively based on the trigger signal to obtain a first digital signal, a second digital signal and a third digital signal; The digital processing module is also used to generate a square wave modulation signal and a trigger signal of a specific frequency.

[0083] For example, the circuit connection diagram of the signal conditioning unit of the X axis is as follows: Figure 4As shown, Ux+ and Ux- are the first analog signals in the form of differential voltage output of the X-axis of the three-axis magnetoresistance module. The signal conditioning unit includes operational amplifiers U1 and U2, resistors R1, R2, R3, R4, R5, R6 and capacitors C1 and C2, and the connection relationship thereof is as follows: one end of the resistor R1 is connected to the inverting output end of the X-axis of the three-axis magnetoresistance module, and the other end is connected to the inverting input end of the operational amplifier U1; one end of the resistor R2 is connected to the positive phase output end of the X-axis of the three-axis magnetoresistance module, and the other end is connected to the positive phase input end of the operational amplifier U1; one end of the resistor R3 is connected to the positive phase output end of the X-axis of the three-axis magnetoresistance module, and the other end is connected to the positive phase input end of the operational amplifier U1; one end of the resistor R4 is connected to the positive phase output end of the X-axis of the three-axis magnetoresistance module, and the other end is connected to the positive phase input end of the operational amplifier U1; one end of the resistor R5 is connected to the positive phase output end of the X-axis of the three-axis magnetoresistance module, and the other end is connected to the positive phase input end of the operational amplifier U1; one end of the resistor R6 is connected to the positive phase output end of the X-axis of the three-axis magnetoresistance module, and the other end is connected to the positive phase input end of the operational amplifier U1; one end of the resistor R7 is connected to the positive phase output end of the X-axis of the three-axis magnetoresistance module, and the other end is connected to the positive phase input end of the operational amplifier U1; one end of the resistor R8 is connected to the positive phase output end of the X-axis of the three-axis magnetoresistance module, and the other end is connected to the positive phase input end of the operational amplifier U1; one end of the resistor R9 is connected to the The inverting input terminal of the operational amplifier U1 is connected to the other end of the output terminal of the operational amplifier U1. One end of the resistor R4 is connected to the non-inverting input terminal of the operational amplifier U1, and the other end is grounded. One end of the resistor R5 is connected to the output terminal of the operational amplifier U1, and the other end is connected to the resistor R6 and the capacitor C2. The other end of the resistor R6 is connected to the non-inverting input terminal of the operational amplifier U2, and the other end of the capacitor C2 is connected to the output terminal of the operational amplifier U2. One end of the capacitor C1 is connected to the non-inverting input terminal of the operational amplifier U2, and the other end is grounded. The output terminal of the operational amplifier U2 is connected to its inverting input terminal. In order to reduce low-frequency drift and reduce system noise, U1 and U2 use zero-drift operational amplifiers, and the resistors used in this embodiment are all precision resistors with low temperature drift coefficients.

[0084] The digital processing module is used to perform digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal and the third digital signal respectively to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction and the third direction.

[0085] It should be noted that if the time of analog-to-digital conversion of different axes is different, it may cause time deviation or data inconsistency between measurement results, thereby affecting the accuracy of the final magnetic field vector. Figure 5 In order to avoid the measurement error caused by the different moments of analog-to-digital conversion of the three axes, in this embodiment, a trigger signal is generated by the digital processing module, and when the synchronous acquisition unit receives the trigger signal, the three axes start sampling at the same time. And the synchronous acquisition unit adjusts the sampling rate to the set value according to the sampling clock signal sent by the digital processing module.

[0086] In other embodiments of the present application, the digital vector magnetoresistive magnetometer also includes a host computer module, which is used to send working parameters to the digital processing module to indirectly control the three-axis magnetoresistive module, square wave modulation unit, signal conditioning unit and synchronous acquisition unit through the digital processing module.

[0087] The digital processing module is also used to control the three-axis magnetic resistance module, square wave modulation unit, signal conditioning unit and synchronous acquisition unit according to the working parameters, and send the magnetic field intensity values ​​and phases of the components of the magnetic field intensity in the first direction, the second direction and the third direction to the host computer module. The working parameters include the frequency of the generated square wave modulation signal, the digital filtering mode of the digital processing module, the sampling rate of the synchronous acquisition unit, the frequency of the generated reference signal, that is, the demodulation frequency, the conversion coefficient of the amplitude into the magnetic field intensity value, and the data upload rate at which the digital processing module sends data to the host computer module.

[0088] It is worth noting that Figure 5 As shown, in other embodiments of the present application, after receiving the working parameters sent by the host computer module, the digital processing module sends the sampling rate in the working parameters to the synchronous acquisition unit, generates a square wave modulation signal according to the frequency of the generated square wave modulation signal and sends it to the square wave modulation unit, generates a first phase reference signal based on the frequency of the reference signal generated in the working parameters, and performs phase shifting (digital synthesis) on the first phase reference signal to obtain a second phase reference signal, and mixes and multiplies the first digital signal, the second digital signal, and the third digital signal with the first phase reference signal and the second phase reference signal through a mixer, respectively, to obtain a first mixing signal and a second mixing signal corresponding to the first digital signal, a third mixing signal and a fourth mixing signal corresponding to the second digital signal, and a fifth mixing signal and a sixth mixing signal corresponding to the third digital signal; Digitally filter the first mixing signal and the second mixing signal, the third mixing signal and the fourth mixing signal, the fifth mixing signal and the sixth mixing signal to obtain a first in-phase component and a first quadrature component, a second in-phase component and a second quadrature component, and a third in-phase component and a third quadrature component respectively; Performing polar coordinate conversion on the first in-phase component and the first quadrature component, the second in-phase component and the second quadrature component, and the third in-phase component and the third quadrature component to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal, and the amplitude and phase of the third digital signal; Based on the relationship between the preset zero drift and temperature, the relationship between the preset voltage-magnetic field conversion coefficient and temperature, and the real-time ambient temperature, digital compensation is performed, and the proportional factor of the voltage-magnetic field conversion (i.e., the voltage-magnetic field conversion coefficient) is adjusted, and the amplitude of the first digital signal, the amplitude of the second digital signal, and the amplitude of the third digital signal are respectively converted into the magnetic field strength value of the first digital signal, the magnetic field strength value of the second digital signal, and the magnetic field strength value of the third digital signal. Finally, according to the data upload rate in the working parameters, the magnetic field strength of each digital signal is uploaded to the upper computer module for output.

[0089] It should be noted that modulation and demodulation can eliminate interference from strong external magnetic fields, and can avoid low-frequency noise from back-end devices such as operational amplifiers and acquisition cards, further improving the signal-to-noise ratio of the magnetoresistive magnetometer, which is crucial to improving the performance of the magnetoresistive magnetometer. In one embodiment, the digital processing module uses FPGA as the core processing chip. The modulation frequency of the square wave modulation signal is set to 100 Hz, the demodulation frequency is set to 100 Hz, the sampling rate of the synchronous acquisition unit is set to 10 kHz, and the data upload rate is set to upload 20 groups of data per second through the host computer module. For example, Figure 6 As shown, the original magnetic measurement signal (i.e., the first analog signal) is a constant magnetic field superimposed with a sine wave with a frequency of 2 Hz, and the direction of the magnetic field to be measured is reversed at 0.5 s. The amplitude of the square wave modulated signal changes with the original magnetic measurement signal. The synchronous acquisition unit converts the square wave modulated signal into a digital signal.

[0090] According to the demodulation frequency, the first phase reference signal , the second phase reference signal , multiplied by the collected digital signal respectively, to obtain two mixed signals. The two mixed signals are digitally filtered to filter out the sum frequency signal, retain the difference frequency signal, and obtain the first in-phase component a and the first orthogonal component b. Convert a and b into polar coordinates, and solve to obtain the amplitude R and phase φ of the input signal. The solution formula is as follows:

[0091] like Figure 6 As shown, after digital demodulation and filtering, the digital demodulation amplitude signal R recovers the amplitude information of the original magnetic measurement signal, and the digital demodulation phase signal Φ represents the direction of the original magnetic measurement signal. At 0.5s, the phase flips by π radians, indicating that the direction is reversed, and the direction flip information of the magnetic field to be measured is correctly demodulated.

[0092] Among them, the process of digital filtering uses a digital low-pass filter and an integral comb filter. Among them, in this embodiment, the digital low-pass filter is set to a finite length unit impulse response filter of 220 orders through the host computer module, with a passband frequency of 10Hz, a stopband frequency of 100Hz, and a stopband attenuation of 60dB. The comb stopband of the integral comb filter is set to the frequency of the demodulation frequency and its higher harmonics. When the filter bandwidth is equivalent to or greater than the demodulation frequency, the demodulated output contains the frequency components of the demodulation frequency and its higher harmonics, and the integral comb filter can attenuate these unwanted harmonic components. Compared with analog filtering, digital filtering can easily realize high-order filters, which usually require a large number of components to be realized in analog circuits, and digital filtering can realize complex types of filtering, such as the integral comb filter of this embodiment, which requires more complex circuits in analog circuits to realize its functions.

[0093] In this embodiment, if Figure 7 As shown, the zero drift curve with temperature is obtained through the above steps 1 and 2, and the least squares method is used to fit the data using MATLAB software to obtain the fitting formula:

[0094] In formula (3), A0 represents the voltage output value (µV) of the digital vector magnetoresistive magnetometer under zero magnetic field, and T represents temperature (°C).

[0095] Through the above steps 1, 2 and 4, the relationship between the voltage-magnetic field conversion coefficient and temperature is obtained. The least squares method is used to fit the data using MATLAB software to obtain the fitting formula:

[0096] In formula (4), A1 represents the relationship between voltage-magnetic field conversion coefficient and temperature (µV / nT), and T represents temperature (℃).

[0097] When the external magnetic field intensity is MnT and the ambient temperature is T°C, the voltage output value U of the digital vector magnetoresistive magnetometer is:

[0098] It should be noted that sensitivity is the voltage-magnetic field conversion coefficient.

[0099] This embodiment uses the zero point of 25°C and the voltage-magnetic field conversion coefficient as the reference: A0 (25) = -99.6µV, A1 (25) = 4.975µV / nT, that is, the conversion coefficient is set to 4.975µV / nT. It can be seen from formula (5) that when digital compensation is not performed, the magnetic field measurement value M2 of the digital vector magnetoresistive magnetometer is as follows:

[0100] In formula (6), M2 is the uncompensated measured value, M is the true value of the magnetic field strength, and the conversion relationship between M2 and M is known. It can be deduced from formula (6) that when the ambient temperature is T0, the digital compensation formula is as follows:

[0101] In formula (7), M3 is the measured value of magnetic field intensity after compensation.

[0102] It should be noted that in this embodiment, the zero point and voltage-magnetic field conversion coefficient of 25°C is used as the reference, and in other embodiments, the zero point and voltage-magnetic field conversion coefficient of other temperatures can be used as the reference. For example, the zero point and voltage-magnetic field conversion coefficient of any temperature between -40°C and 50°C can be used as the reference, and this application does not limit this.

[0103] Exemplarily, in another embodiment, the ambient temperature is 5°C and the external magnetic field strength is 10000nT. The resolution of the synchronous acquisition unit is 24 bits and the full-scale input is 5V, that is, the acquisition accuracy of the synchronous acquisition unit is 0.3µV, and the digital compensation accuracy is approximately 0.3 / 4.975=0.06nT. Under this condition, the voltage output value of the digital vector magnetoresistive magnetometer is: U=10000×A1(5)+A0(5)=49909.5µV. According to formula (6), when digital compensation is not performed, the magnetic field measurement value M2=(U+99.6) / 4.975=10052.1nT. When performing digital compensation, the fitting parameters of the zero drift and the relationship between the voltage-to-magnetic field conversion coefficient and the temperature drift at the ambient temperature are calculated first. From formulas (3), (4) and (7), it can be seen that at 5°C, A0 = -40.5µV, A1 = 4.995µV / nT, and the compensated magnetic field measurement value M3 = 10000.02nT, which differs from the actual value by 0.02nT.

[0104] In another embodiment, the ambient temperature is 5°C and the external magnetic field strength is 10000nT. The resolution of the synchronous acquisition unit is 12 bits and the full-scale input is 5V, that is, the acquisition accuracy of the synchronous acquisition unit is 1221µV, and the digital compensation accuracy is about 1221 / 4.975=245nT. Under this condition, limited by the acquisition accuracy of the synchronous acquisition unit, the voltage output value of the digital vector magnetoresistive magnetometer is 50049µV. According to formula (6), when digital compensation is not performed, the magnetic field measurement value M2=(U+99.6) / 4.975=10080.1nT. When performing digital compensation, the fitting parameters of the zero point drift and the relationship between the voltage-to-magnetic field conversion coefficient and the temperature drift at the ambient temperature are calculated first. From formulas (3), (4) and (7), it can be seen that at 5°C, A0=-40.5µV, A1=4.995µV / nT, and the compensated magnetic field measurement value M3=10027.9nT, which differs from the actual value by 27.9nT.

[0105] It can be seen from the above embodiments that the accuracy of digital compensation is limited by the acquisition accuracy of the synchronous acquisition unit and the overall noise of the system. Therefore, by using a high-resolution synchronous acquisition unit and a low-noise design, the accuracy of digital compensation can be less than 1nT, which is much higher than the compensation accuracy of analog devices. Moreover, for magnetoresistive sensor chips with different temperature drift characteristics, the fitting parameters can be obtained by least squares fitting, and the compensation method has better versatility than analog devices.

[0106] In other embodiments of the present application, the signal conditioning unit includes a differential amplifier circuit and an active low-pass filter circuit, and the operational amplifier in the differential amplifier circuit is a zero-drift operational amplifier, and the resistor in the signal conditioning unit is a low-temperature drift resistor.

[0107] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0108] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for measuring vector magnetic field strength, characterized in that: Applied to a digital vector magnetoresistive magnetometer, the method comprises: According to the magnetic field strength of the environment in which the digital vector magnetoresistive magnetometer is located, a first analog signal, a second analog signal and a third analog signal are obtained, wherein the first analog signal represents a component of the magnetic field strength in a first direction, the second analog signal represents a component of the magnetic field strength in a second direction, and the third analog signal represents a component of the magnetic field strength in a third direction, and the first direction, the second direction and the third direction are perpendicular to each other; Performing signal processing on the first analog signal, the second analog signal and the third analog signal respectively to obtain a first digital signal, a second digital signal and a third digital signal; The first digital signal, the second digital signal and the third digital signal are respectively digitally orthogonally demodulated and digitally compensated to obtain the magnetic field intensity values ​​and phases of the magnetic field intensity in the first direction, the second direction and the third direction.

2. The method for measuring vector magnetic field strength according to claim 1, characterized in that: The performing digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal and the third digital signal respectively to obtain the magnetic field intensity values ​​and phases of the components of the magnetic field intensity in the first direction, the second direction and the third direction includes: Generate a first phase reference signal and a second phase reference signal based on a demodulation frequency input by an external device; Performing digital quadrature demodulation based on the first digital signal, the second digital signal, the third digital signal, the first phase reference signal, and the second phase reference signal to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal, and the amplitude and phase of the third digital signal; Based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage-magnetic field conversion coefficient and temperature, and the real-time ambient temperature, the amplitude of the first digital signal, the amplitude of the second digital signal, and the amplitude of the third digital signal are respectively converted into the magnetic field strength value of the first digital signal, the magnetic field strength value of the second digital signal, and the magnetic field strength value of the third digital signal, and digital compensation is performed.

3. The method for measuring vector magnetic field strength according to claim 2, characterized in that: The digital orthogonal demodulation is performed based on the first digital signal, the second digital signal, the third digital signal, the first phase reference signal and the second phase reference signal to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal and the amplitude and phase of the third digital signal, including: Mix and multiply the first digital signal, the second digital signal and the third digital signal with the first phase reference signal and the second phase reference signal, respectively, to obtain a first mixing signal and a second mixing signal corresponding to the first digital signal, a third mixing signal and a fourth mixing signal corresponding to the second digital signal, and a fifth mixing signal and a sixth mixing signal corresponding to the third digital signal, respectively; Digitally filter the first mixing signal and the second mixing signal, the third mixing signal and the fourth mixing signal, the fifth mixing signal and the sixth mixing signal to obtain a first in-phase component and a first quadrature component, a second in-phase component and a second quadrature component, and a third in-phase component and a third quadrature component respectively; The first in-phase component and the first quadrature component, the second in-phase component and the second quadrature component, and the third in-phase component and the third quadrature component are transformed into polar coordinates to obtain the amplitude and phase of the first digital signal, the amplitude and phase of the second digital signal, and the amplitude and phase of the third digital signal.

4. The method for measuring vector magnetic field strength according to claim 2, characterized in that: Based on the relationship between the preset zero drift and the temperature, the relationship between the preset voltage-magnetic field conversion coefficient and the temperature, and the real-time ambient temperature, the amplitude of the first digital signal, the amplitude of the second digital signal, and the amplitude of the third digital signal are respectively converted into the magnetic field intensity value of the first digital signal, the magnetic field intensity value of the second digital signal, and the magnetic field intensity value of the third digital signal, and digital compensation is performed, including: Based on the relationship between the preset voltage magnetic field conversion coefficient and the temperature, the amplitude of the first digital signal, the amplitude of the second digital signal and the amplitude of the third digital signal are converted into the magnetic field intensity value of the first digital signal, the magnetic field intensity value of the second digital signal and the magnetic field intensity value of the third digital signal respectively; Based on the relationship between the preset zero point drift and temperature, the relationship between the preset voltage magnetic field conversion coefficient and temperature, and the real-time ambient temperature, the magnetic field strength value of the first digital signal, the magnetic field strength value of the second digital signal, and the magnetic field strength value of the third digital signal are digitally compensated.

5. The method for measuring vector magnetic field strength according to claim 2, characterized in that: The method of generating a first phase reference signal and a second phase reference signal based on a demodulation frequency input by an external device comprises: Generate a first phase reference signal based on a demodulation frequency input by an external device; The first phase reference signal is phase-shifted to obtain a second phase reference signal.

6. The method for measuring vector magnetic field strength according to claim 2, characterized in that: The vector magnetic field strength measurement method further includes: heating the digital vector magnetoresistive magnetometer to a first temperature, and recording a first relationship between a measurement value of the digital vector magnetoresistive magnetometer and temperature during cooling to a second temperature under the first magnetic field strength; Cooling the digital vector magnetoresistive magnetometer to a third temperature, and recording a second relationship between a measurement value of the digital vector magnetoresistive magnetometer and temperature during a process of naturally heating up to a second temperature under the first magnetic field strength; Based on the first relationship and the second relationship, obtaining a relationship between a preset zero drift and a temperature; heating the digital vector magnetoresistive magnetometer to a first temperature, and recording a third relationship between a voltage-to-magnetic-field conversion coefficient and temperature of the digital vector magnetoresistive magnetometer during cooling to a second temperature under a second magnetic field strength; Cooling the digital vector magnetoresistive magnetometer to a third temperature, and recording a fourth relationship between a voltage-to-magnetic-field conversion coefficient and temperature of the digital vector magnetoresistive magnetometer during a process of naturally heating to the second temperature under a second magnetic field strength; Based on the third relationship and the fourth relationship, a relationship between a preset voltage-magnetic field conversion coefficient and temperature is obtained.

7. The method for measuring vector magnetic field strength according to claim 1, characterized in that: The processing of the first analog signal, the second analog signal and the third analog signal to obtain a first digital signal, a second digital signal and a third digital signal comprises: Generate a square wave modulation signal of a specific frequency, and based on the square wave modulation signal, perform square wave modulation on the first analog signal, the second analog signal, and the third analog signal respectively; performing differential amplification and filtering on the first analog signal, the second analog signal and the third analog signal respectively; Based on the trigger signal, the first analog signal, the second analog signal and the third analog signal are respectively converted into digital form to obtain a first digital signal, a second digital signal and a third digital signal.

8. A digital vector magnetoresistive magnetometer, characterized in that: The digital vector magnetoresistive magnetometer is used to measure the magnetic field strength of a three-dimensional vector magnetic field. The digital vector magnetoresistive magnetometer comprises: Three-axis magnetoresistive module, signal processing module and digital processing module; The three-axis magnetic resistance module is used to obtain a first analog signal, a second analog signal and a third analog signal according to the magnetic field strength of the environment, wherein the first analog signal represents the component of the magnetic field strength in a first direction, the second analog signal represents the component of the magnetic field strength in a second direction, and the third analog signal represents the component of the magnetic field strength in a third direction, and the first direction, the second direction and the third direction are perpendicular to each other; The signal processing module is used to perform signal processing on the first analog signal, the second analog signal and the third analog signal respectively to obtain a first digital signal, a second digital signal and a third digital signal; The digital processing module is used to perform digital orthogonal demodulation and digital compensation on the first digital signal, the second digital signal and the third digital signal respectively to obtain the magnetic field strength value and phase of the magnetic field strength in the first direction, the second direction and the third direction.

9. The digital vector magnetoresistive magnetometer according to claim 8, characterized in that: The signal processing module includes a square wave modulation unit, a signal conditioning unit and a synchronous acquisition unit; The square wave modulation unit is used to perform square wave modulation on the first analog signal, the second analog signal and the third analog signal respectively based on the square wave modulation signal; The signal conditioning unit is used to perform differential amplification and filtering on the first analog signal, the second analog signal and the third analog signal respectively; The synchronous acquisition unit is used to perform analog-to-digital conversion on the first analog signal, the second analog signal and the third analog signal respectively based on the trigger signal to obtain a first digital signal, a second digital signal and a third digital signal; The digital processing module is also used to generate a square wave modulation signal and a trigger signal of a specific frequency.

10. The digital vector magnetoresistive magnetometer according to claim 9, characterized in that: The signal conditioning unit comprises a differential amplifier circuit and an active low-pass filter circuit, the operational amplifier in the differential amplifier circuit is a zero-drift operational amplifier, and the resistor in the signal conditioning unit is a low-temperature drift resistor.

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